Early in mammalian ovarian follicular development, granulosa cells associate with both the oocyte and the basal lamina that circumscribes the follicle. Later, however, during the development of the antrum, the granulosa cells become divided into two major groups: those in contact with the oocyte (cumulus granulosa cells) and those in contact with the basal lamina (mural granulosa cells). Although abundant information on the role of granulosa cells in oocyte development has emerged in the last decade, little is known of how the oocyte or basal lamina might participate in granulosa cell development. The principal hypothesis to be tested in the proposed studies is that granulosa cell development and function are modulated by contact with the oocyte or the basal lamina. The first specific aim is to determine whether removal of the oocyte affects the development and function of granulosa cells from preantral follicles. A unique system has been developed to assess the effects of oocytectomy on cultured oocyte-granulosa cell complexes from 10 day old mice. Potential effects will assessed in terms of cell proliferation, protein synthetic patterns, and the responses of the cells to gonadotropin stimulation. The cumulus and mural granulosa and antral follicles produce some type-specific proteins and respond in some different ways to hormonal stimulation. These differences could be promoted by many diverse developmental stimuli. This proposal focuses on two factors that could participate in the differential expression of mural and cumulus granulosa cell-specific proteins; (1) development from different progenitor cells, and (2) association with either the oocyte or the basal lamina. Aggregation chimeras will be prepared from 8-cell embryos of two congenic lines expression- expressing different isozyme alleles at the glucose-6-phosphate isomerase-1 locus, and the expression of these alleles in mural and cumulus granulosa cells in female chimeras will be determined to ascertain whether these two cell types develop from on or more progenitor cells that initially contact the primordial types develop from one or more progenitor cells that initially contact the primordial oocyte during primitive follicle formation. To determine whether contact with basal lamina promotes development of mural granulosa cells, and whether the absence of such promotes development as cumulus granulosa cells, granulosa cell development will be assessed by 2-dimensional polyacrylamide gel electrophoresis of proteins synthesized by cells grown in contact with basal lamina or under conditions that prevent cell adhesion to substratum.